Download Healthcare-Associated Pertussis Outbreak in

Brief Report
Healthcare-Associated Pertussis Outbreak in
Arizona: Challenges and Economic Impact, 2011
Seema Yasmin,1 Rebecca Sunenshine,3 Kristine M. Bisgard,2 Caleb Wiedeman,4,a Alice Carrigan,3
Tammy Sylvester,3 Greg Garcia,3 Karen Rose,3 Sun Wright,3 Susan Miller,3 Rachel De La Huerta,3 Helen Houser,3
Aarikha D’Souza,4,b Shoana Anderson,4 Kathleen Howard,5 Kenneth Komatsu,4 and Ronald Klein3
1
Epidemic Intelligence Service, and 2Office of Surveillance, Epidemiology and Laboratory Services, Centers for Disease Control
and Prevention, Atlanta, Georgia; 3Maricopa County Department of Public Health, 4Arizona Department of Health Services, and
5
St Joseph’s Hospital and Medical Center, Phoenix, Arizona
Corresponding Author: Seema Yasmin, MB BChir, 150 N 18th Ave, Ste 140, Phoenix, AZ 85007.
E-mail: [email protected].
Presented in part: 61st Epidemic Intelligence Service Conference, Atlanta, Georgia, April 16–20, 2012.
a
Present Affiliation: Tennessee Department of Health, Nashville, Tennessee.
b
Present Affiliation: Banner Desert Medical Center and Cardon Children's Medical Center, Mesa, Arizona.
Received July 19, 2012; accepted December 13, 2012; electronically published January 30, 2013.
An outbreak investigation identified 15 pertussis cases among 5 infants and 10 healthcare professionals
at 1 hospital’s neonatal intensive care unit (NICU). The cost of the outbreak to this hospital was $97 745.
Heightened awareness of pertussis in NICUs is key to preventing healthcare-associated spread and
minimizing outbreak-control-related costs. Bordetella pertussis is a highly communicable bacterial pathogen
that causes a prolonged cough illness and is spread by respiratory droplet transmission. Infants aged 6
months are most susceptible to B pertussis infection and pertussis-associated complications, including
pneumonia, encephalopathy, and death, and are commonly hospitalized for treatment [1]. Despite a
universal pertussis vaccination program, 27 550 pertussis cases were reported in the United States during
2010 [2]. Pertussis outbreaks in healthcare settings can be challenging and costly to control [3]. On
September 13, 2011 and September 15, 2011, 3 pertussis cases, including 2 confirmed by B pertussis
isolation, among preterm infants discharged 30 days previously from a 71-bed NICU of a general hospital
(NICU A) were reported by Hospital B, a large pediatric facility, to Maricopa County Department of Public
Health. This report describes the outbreak, examines outbreak-associated costs and risk factors that might
have contributed to healthcare-associated transmission, and provides guidance to prevent outbreaks in
healthcare settings.
Key words.
disease outbreak; healthcare worker-patient transmission; infants; neonates; pertussis.
METHODS
Case Investigation and Outbreak Response
Hospital A called the pediatricians of 40 exposed infants
requesting that they inform parents of their infant’s exposure to pertussis in the neonatal intensive care unit of a
general hospital (NICU A). Hospital A and the Maricopa
County Department of Public Health sent a letter to
these parents of exposed infants informing them of pertussis exposure, signs, and symptoms. Case-finding was
performed using a standardized telephone questionnaire
administered to NICU A healthcare providers (HCPs),
who were furloughed from work because of cough
illness, and to parents of exposed infants. A probable
case was defined as cough illness for 14 days in a
person associated with NICU A from July 28, 2011 to
September 19, 2011. A confirmed case met the probable
case definition and was laboratory-confirmed by (1) a
positive polymerase chain reaction (PCR) result for
Journal of the Pediatric Infectious Diseases Society, Vol. 3, No. 1, pp. 81–4, 2014. DOI:10.1093/jpids/pis136
Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society 2013. This work is written by US Government employees and is in the
public domain in the US.
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Yasmin et al
Bordetella pertussis DNA, (2) isolation of B pertussis, or
(3) epidemiologic linkage to a laboratory-confirmed case.
We reviewed records of infants with pertussis in NICU
A, assessed the infant’s age at the time of cough or apnea
onset, investigated potential sources of transmission, and
mapped case locations. This study underwent review by
the Centers for Disease Control and Prevention’s (CDC)
Scientific Education and Professional Development
Program Office.
Hospital Costs
We assessed Hospital A costs (tetanus toxoid, reduced
diphtheria toxoid, and acellular pertussis [Tdap] booster
vaccine, vaccine administration, postexposure prophylaxis [PEP], and laboratory and labor costs) incurred in controlling the outbreak. Cost of Tdap vaccine ($29/dose)
and administration ($10/administration) for HCPs were
obtained from the CDC. The hospital acquisition price
for PEP ($13.16 for azithromycin; $9 for trimethoprimsulfamethoxazole) was used. HCP furlough costs were
calculated by multiplying the number of days in furlough, the number of HCPs furloughed, and a normal
work shift (8 hours/day) by mean hourly earnings for
full-time Arizona hospital HCPs ($35.48) [4]. Costs incurred by other institutions were not included.
RESULTS
Descriptive Epidemiology
Forty infants were hospitalized in NICU A from July 28,
2011 to September 19, 2011; parents of 35 of these
infants (88%) were interviewed. Of 39 NICU A HCPs furloughed for cough illness, 35 (90%) were interviewed. We
identified 15 pertussis cases including 5 infants (Table 1)
and 10 NICU A HCPs. Three cases were laboratoryconfirmed at HealthCare Clinical Laboratories (Stockton,
CA) by PCR or isolation by culture. The remaining 12
cases were confirmed with compatible clinical findings
and by epidemiologic linkage to NICU A.
Exposure and Contact Investigations
The index case occurred in a 4-week-old female who had
been born at 28 weeks gestation and resided at NICU A
from June 25, 2011 to September 9, 2011. She experienced apnea (ascribed to gastroesophageal reflux disease)
on July 28, 2011; pertussis was not suspected. From
August 7, 2011 to August 9, 2011, the patient had been
located adjacent to Patients 2 and 3; the distance
between NICU A beds where they were co-located was
16 inches; all 3 infants had shared the same 2 nurses
during this time. The index patient’s cough began on
August 14, 2011 and lasted 26 days; she had not been
isolated at any time during her admission at NICU A.
The index patient’s illness was confirmed after transfer to
Hospital B on September 9, 2011 when a nasopharyngeal swab collected on September 14, 2011 was positive
by pertussis PCR; B pertussis was isolated by culture 1
week later. The index patient received azithromycin on
September 14, 2011 (32 days after cough onset, and 49
days after apnea onset). Diagnosis of Patients 2–5 were
similarly delayed (Table 1). Patient 4’s sibling also had
pertussis symptoms from August 4, 2011 to August 19,
2011 and visited Patient 4 in NICU A while ill. Ten
HCPs at NICU A had an illness that met the pertussis
case definition (age range: 32–50 years; median age 39.5
years; 6 [60%] female); all worked during cough illness.
Site Visit and Location Mapping
Two of 8 sinks in the area where the index patient and
Patients 2 and 3 had been located were obstructed by
carts and trash cans. Infants were routinely moved within
the unit, and infant location had not been accurately recorded. Hospital policy requiring HCPs with acute respiratory illness to take personal leave had not been
enforced. NICU visitors were not screened for cough
illness before entry, and no signage was posted requesting
ill visitors to refrain from entering NICU A.
Costs to Hospital A
Thirty-nine NICU A HCPs had been furloughed due to
cough illness for 5 days ($55 349). Three hundred sixtyfive HCPs and 40 infants received PEP ($5297) and underwent laboratory testing for pertussis ($7420); 330
HCPs required pertussis vaccine ($12 870). Hospital A
staff worked an additional 455 hours on outbreak management ($16 809). The approximate total outbreak cost
to Hospital A was $97 745, excluding the costs incurred
by Hospital B and state and local health departments.
HCP furloughs constituted 57% of this cost.
DISCUSSION
This healthcare-associated pertussis outbreak with 15
identified cases cost 1 hospital approximately $100 000.
Forty infants hospitalized in a NICU were exposed to
pertussis and required PEP. This investigation adds to
prior work documenting costs incurred by hospitals responding to pertussis outbreaks and the ease with which
pertussis can be transmitted within the healthcare setting
[3, 5, 11]. In 2 Washington outbreaks, the hospital cost
per case ranged from $30 282 to $43 893 [6], which is
considerably more than the approximately $6500 per
case associated with NICU A.
Multiple factors contributed to this healthcareassociated pertussis outbreak. First, delays occurred in
diagnosis and isolation of cases. Delayed diagnosis of
Healthcare-Associated Pertussis Outbreak
Table 1. Characteristics of Pertussis Cases in Infants Associated With NICU A, 2011a
Patient
Gestational
Age (weeks)
1
2
28
28
3
4
5
Median value
24
39
28
28
Comorbidities
LBW
LBW, trachea-esophageal
fistula, PDA
LBW, PDA
Hydrocephalus
LBW
-
Date of Pertussis
Cough/Apnea Onset
(age in weeks)
Length of NICU
A Admission (days)
July 28 (4)
August 24 (12)
August 19 (15)
August 11 (1)
September 19 (4)
(4)
Pertussis Test Date (days
post-cough/apnea onset)
77
91
September 14 (49)
September 7 (15)
109
16
10
77
August 25 (7)
September 30 (51)
September 30 (12)
(15)
Abbreviations: LBW, low birth weight; NICU, neonatal intensive care unit; PDA, patent ductus arteriosus.
a
All infant case-patients were female.
infections has been identified as one of the most important factors in prolonged healthcare-associated outbreaks
[7]. Second, infants were located in close proximity to
one another and shared the same nurse when 1 infant
was infectious. Third, HCPs worked during cough
illness, and fourth, visitors entered the NICU when ill.
Previous pertussis outbreaks have been attributed to
cough illness among hospital visitors [8]; however, after
outbreaks in high-risk settings (eg, nurseries), visitor
screening for cough has been successfully implemented to
prevent infants’ exposure. Limiting staff and visitor
access to high-risk areas and discouraging parents from
having contact with infants other than their own infant
are additional strategies to be considered [9].
Lack of HCP pertussis vaccination documentation contributed to costs associated with this outbreak. HCP vaccination can protect against pertussis and thereby reduce
spread and costs associated with pertussis outbreak management [3]. The Advisory Committee on Immunization
Practices recommends the Tdap booster vaccine be administered to HCPs, and recorded, especially for HCPs
working with infants aged 12 months, because of the
increased risk for acquiring pertussis in the healthcare
setting and potential for transmitting pertussis to highrisk patients [10].
One limitation of this study was an underestimation of
outbreak-related costs because costs related to liability or
increased duration of hospitalization were not included.
First, costs incurred by state and local health departments, private and public insurance, another receiving
hospital, or indirect costs borne by patients and families
were not included. Second, we were unable to interview
and apply the case definition to NICU A visitors because
visitor information was not documented by the hospital.
Third, the primary mode of healthcare-associated transmission during this outbreak could not be discerned
because of poorly defined pertussis symptom onset, especially among HCPs. Transmission might have included
patient-to-HCP, patient-to-patient, patient-to-visitor, and
HCP-to-patient transmission. Although infants usually
do not have a strong enough cough to reach other patients, the close proximity of neonates in NICU A, especially when being handled by HCPs during feeding,
increases the possibility of patient-to-patient spread in
this outbreak. Regardless of how the index patient
became infected, our data indicate that transmission to
2 other infants occurred in NICU A.
This costly healthcare-associated pertussis outbreak
might have been precipitated by the lack of strategies
needed to prevent the spread of vaccine-preventable diseases to vulnerable populations in medical settings, including: (1) increasing pertussis awareness among
providers, especially among patient populations who
present with apnea (eg, infants); (2) convenient access
and documenting of pertussis vaccine for HCPs; (3) allowing only HCPs with evidence of pertussis booster
vaccine to provide care to infants aged 6 months; and
(4) screening visitors for cough illness upon entry to the
NICU [9, 12], and instituting a screening plan to identify
suspected pertussis cases for immediate isolation.
Acknowledgments
Disclaimer. The findings and conclusions in this report are those of
the authors and do not necessarily represent the official position of
the Centers for Disease Control and Prevention or the institutions
with which authors are affiliated.
Financial support. This work was funded by the Centers for
Disease Control and Prevention, Arizona Department of Health
Services, and Maricopa County Department of Public Health.
Potential conflict of interest. All authors: No reported conflicts.
All authors have submitted the ICMJE Form for Disclosure of
Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
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